voltage controlled oscillators
DESCRIPTION
Voltage Controlled Oscillators. Yousef Shakhsheer 3/29/2011. VCOs. Two criteria Generates a periodic output. Needs self-sustaining oscillation mechanism;. Important Metrics. Frequency Power Tunability (Range and linearity) Jitter Figure of Merit. Three Types of Oscillators. LC-Tank - PowerPoint PPT PresentationTRANSCRIPT
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Voltage Controlled Oscillators
Yousef Shakhsheer3/29/2011
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VCOs
Two criteria• Generates a periodic output.• Needs self-sustaining oscillation mechanism;
feedback) negative a is, ( 180 be tohas )H(j then negative, is DCin loop theif *
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sBarkhausen
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Important Metrics
• Frequency• Power• Tunability (Range and linearity)• Jitter• Figure of Merit
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Three Types of Oscillators
• LC-Tank
• Ring oscillator
• Crystal Oscillator
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Important Issues
• Inductors - inductance modeling and modeling of losses. Topology
• Varactors - Topology• Process Variation • Temperature
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[1] A Sub-1–V 4-GHz CMOS VCO and a 12.5-GHz Oscillator for Low-Voltage and High-Frequency
Ahmed H. Mostafa, Mourad N. El-Gamal,& Ramez A. Rafla
7Mostafa et al, “A Sub-1–V 4-GHz CMOS VCO and a 12.5-GHz Oscillator for Low-Voltage and High-Frequency”
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Topologies4-,5- GHz
Varactor Tuning10.5-,12.5- GHz
Back-gate Tuning
Mostafa et al, “A Sub-1–V 4-GHz CMOS VCO and a 12.5-GHz Oscillator for Low-Voltage and High-Frequency”
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[2] 1-V Ultra-Low-Power CMOS LC VCO for UHF Quadrature Signal Generation
Zheng Wang, Huseyin S. Savci, Numan S. Dogan
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Proposed Topology
Wang et al, “1-V Ultra-Low-Power CMOS LC VCO for UHFQuadrature Signal Generation”
11Wang et al, “1-V Ultra-Low-Power CMOS LC VCO for UHFQuadrature Signal Generation”
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[3] A Low-Complexity, Low-Phase-Noise, Low-Voltage Phase-Aligned Ring Oscillator in 90 nm Digital CMOS
Jonathan Borremans, Julien Ryckaert, Claude Desset, Maarten Kuijk, Piet
Wambacq, and Jan Craninckx,
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Ring Oscillators
Problem:• Inductors are hard to
design• Jitter added over time in
ring oscillatorRing Oscillator:• Reset to reduce jitter,
noise, power, etc• Very simple circuitry
Borremans et al, “A Low-Complexity, Low-Phase-Noise, Low-Voltage Phase-Aligned Ring Oscillator in 90 nm Digital CMOS”
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Results
Borremans et al, “A Low-Complexity, Low-Phase-Noise, Low-Voltage Phase-Aligned Ring Oscillator in 90 nm Digital CMOS”
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[4] A Low-Power, Process-and-Temperature-Compensated Ring Oscillator With Addition-Based Current Source
Xuan Zhang, and Alyssa B. Apsel
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PVT Variation
Change from single transistor to current source for PVT
Zhang et al, “A Low-Power, Process-and-Temperature-Compensated Ring Oscillator With Addition-Based Current Source”
17Zhang et al, “A Low-Power, Process-and-Temperature-Compensated Ring Oscillator With Addition-Based Current Source”
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Variation
Zhang et al, “A Low-Power, Process-and-Temperature-Compensated Ring Oscillator With Addition-Based Current Source”
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[5] Low-Voltage, Low-Power and Low Phase Noise 2.4 GHz VCO for Medical Wireless
Telemetry
Ahmed Fakhr, M. Jamal Deen and Hubert deBruin
Fakhr et al, “Low-Voltage, Low-Power and Low Phase Noise 2.4 GHz VCO for Medical Wireless Telemetry”
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Sub - VT
Fakhr et al, “Low-Voltage, Low-Power and Low Phase Noise 2.4 GHz VCO for Medical Wireless Telemetry”
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Sub-VT
Fakhr et al, “Low-Voltage, Low-Power and Low Phase Noise 2.4 GHz VCO for Medical Wireless Telemetry”
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Crystal
• 8.0 MHz - 50.0 MHz
• 10 - 100 µW
• http://www.abracon.com/Resonators/abm3b.pdf
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Summing it all up
[1] [2] [3] [4] [5]
Technology .25 um .180 um .090 um .090 um .180 um
Voltage .85 V 1 V .5 V 1 V .4 V
Max Freq 4 GHz 1.6 GHz 400 MHz 1.8 GHz 2.4 GHz
Phase Noise
-84.7 @ 100 KHz
-121 @ 1 MHz
-119 @ 200 Hz
-109.76 @ 10 MHz
-123 @ 1 MHz
Power 4.08 mW 105 uW 1.8 mW 87 uW 41 uW
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Other Good Resources
• Razavi’s Book• Perrott’s slides